Effects of Surface Deposition, Hole Blockage, and Thermal Barrier Coating Spallation on Vane Endwall Film Cooling

Sundaram, Narayan K.; Thole, Karen A.

doi:10.1115/1.2720485

Cited by 52 publications

(15 citation statements)

References 25 publications

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“…The particulate can also stick to the surface, creating deposit structures and possibly blocking the film cooling holes. A study by Sundaram et al [17] looked at the latter two cases on an endwall of two scaled up passages of a first stage vane. A constant temperature difference of 40 K between the coolant and main flow was held during the test as measured by thermocouple rakes.…”

Section: 22: Film Cooling Studiesmentioning

confidence: 99%

The Effect of Particle Size on Deposition in an Effusion Cooling Geometry

Wolff

Bowen

Bons

2018

2018 AIAA Aerospace Sciences Meeting

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The effect of particle size on particle accumulation within an effusion cooling geometry common to gas turbines was investigated experimentally and computationally.A flat plate with an effusion cooling hole array based on a gas turbine combustor liner was subjected to particulate laden flow in an accelerated deposition facility. The tests were conducted at an engine relevant plate temperature of 1118 K, coolant temperature of 950 K, and held at a constant pressure ratio of 1.03 (cavity to ambient). To elucidate the effect of particle size, six unique size distributions of Arizona Road Dust (ARD) smaller than 20 micron were introduced to the flow independently. Experiments were also conducted in which two different dust size distributions were sequentially delivered to the test article. These experiments clearly indicate that the smallest particles within the range tested accumulate within the hole creating deposit structures and blocking the effusion holes. They also indicate that larger particles within this range can have an erosive effect on the deposit structures as they build, changing the structure's morphology and blockage behavior.Computational fluid domains were developed to replicate the test article geometry before and after a test to investigate the effect that deposit structures have on deposition.Particles were introduced to these domains after reaching a steady solution and were tracked through the solution with a Lagrangian trajectory solver. The impact locations of iv the particles were recorded and a particle sticking model was employed to determine if the particles stick or rebound. The domain with the clean hole showed that the smallest particles impact and were prone to sticking in the area where deposits form experimentally. As the particles increase in size, the number of impacts and likelihood of sticking decreased. The domain with scoop deposit structures showed that these structures can change the particle impact trajectories influencing the buildup process.Overall, this body of work shows that particle size distribution has a first order effect on the blockage caused by particle deposition in effusion cooling geometries. The observation that 0.5-3 μm particles are primarily responsible for blockage while large particles can reduce deposit structure size highlights the complexity of particle deposition. This has significant implications for future work, particularly high fidelity modeling.v

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Section: 22: Film Cooling Studiesmentioning

confidence: 99%

The Effect of Particle Size on Deposition in an Effusion Cooling Geometry

Wolff

Bowen

Bons

2018

2018 AIAA Aerospace Sciences Meeting

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“…Sundaram and Thole [9] have studied the effect of deposition on cooling effectiveness on shower head and endwall film cooling, respectively. The group utilizes low melting temperature wax to simulate deposition.…”

Section: List Of Tablesmentioning

confidence: 99%

The Effect of Film Cooling on Nozzle Guide Vane Deposition

Bonilla

Clum

Lawrence

et al. 2013

Volume 3B: Heat Transfer

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An accelerated deposition test facility was used to study the relationship between film cooling, surface temperature, and particle temperature at impact on deposit formation. Tests were run at gas turbine representative inlet Mach numbers (0.1) and temperatures (1090°C). Deposits were created from lignite coal fly ash with median diameters of 1.3 and 8.8µm. Two CFM56-5B nozzle guide vane doublets, comprising three full passages and two half passages of flow, were utilized as the test articles. Tests were run with different levels of film cooling back flow margin and coolant temperature.Particle temperature upon impact with the vane surface was shown to be the leading factor in deposition. Since the particle must traverse the boundary layer of the cooled vane before impact, deposition is directly affected by the film and metal surface temperature as well. Film coolant jet strength showed only minor effect on deposit patterns on the leading edge. However, larger Stokes number (resulting in higher particle impact temperature) corresponded with increased deposit coverage area on the shower head region. Additionally, infrared measurements showed a strong correlation between regions of greater deposits and elevated surface temperature on the pressure surface.Thickness distribution measurements also highlighted the effect of film cooling by showing reduced deposition immediately downstream of cooling holes. A set of secondary tests were also conducted to briefly study the effect of Stokes number on leading edge deposition with no cooling, in order to support conclusions from the primary iii tests. It was found that larger Stokes number led to an increase in rate of deposition due to a greater number of particles being able to follow their inertial trajectories and impact the vane. Implications for engine operation in particulate-laden environments are discussed.iv Dedicated to my parents

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“…Dunn et al also noted that aircraft engines that ingest particle laden flow have increased difficulty in restarting and that engines exposed to sufficient levels of particulate can be damaged beyond repair. Sundaram and Thole [5] studied the effects of deposition on film cooling and found that film cooling effectiveness degrades as deposition forms near and in film cooling holes. Lewis et al [6] found that the location of deposition around film cooling holes can affect the heat transfer.…”

Section: Introductionmentioning

confidence: 98%

Computational Modeling of High Temperature Deposition in Gas Turbine Engines with Experimental Validation

Lawrence

Casaday

Lageman

et al. 2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Four deposition models--critical velocity, critical viscosity, and two forms of elastoviscoplasticity--were studied to determine their applicability to deposition in gas turbine engines. An experimental rig was constructed to determine the coefficient of restitution and sticking probability of bituminous ash particles. The coefficient of restitution was found to decrease for both increased particle temperature and increased particle impact velocity, matching the trends of similar tests performed with quartz particles. The sticking probability was observed to be highest at the lowest observed particle kinetic energies. These trends highlight the shortcomings of both the critical velocity and critical viscosity models. No results were found to discount either of the elastoviscoplasticity models, but more data must be analyzed to confirm if either of these models correctly describes ash particle impact physics in gas turbine engine environments. Nomenclature A= constant used to define critical viscosity model B = constant used to define critical viscosity model D = particle diameter E = effective modulus of elasticity ‫ܧ‬ = particle modulus of elasticity ‫ܧ‬ ௦ = surface modulus of elasticity e = coefficient of restitution KE = kinetic energy k = apparent plastic flow consistency m = particle mass n = apparent plastic flow index P S = probability of particle sticking r = particle radius T P = temperature of particle ‫ݒ‬ = normal critical velocity ‫ݒ‬ = final/rebound velocity ‫ݒ‬ = initial/impact velocity ܹ = work of adhesion ߛ = surface energy adhesion parameter η = ratio of initial tangential velocity to initial normal velocity ߟ = particle Poission's ratio ߟ ௦ = surface Poission's ratio µ = viscosity of particle µ crit = viscosity of particle at critical sticking temperature µ Tp = viscosity of particle at temperature ߩ = particle density ߪ ො = flow stress ߪ = yield stress ߪ = uniaxal yield stress

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Effects of Surface Deposition, Hole Blockage, and Thermal Barrier Coating Spallation on Vane Endwall Film Cooling

Cited by 52 publications

References 25 publications

The Effect of Particle Size on Deposition in an Effusion Cooling Geometry

The Effect of Particle Size on Deposition in an Effusion Cooling Geometry

The Effect of Film Cooling on Nozzle Guide Vane Deposition

Computational Modeling of High Temperature Deposition in Gas Turbine Engines with Experimental Validation

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